Please find the error

%Write a function called max_sum that takes v as a row vector of numbers, & n,a postive integer as inputs.The function needs to find n consecutive
%elements of v whose sum is the largest possible.If multiple such sequence exists in v,max_sum returns first one.The function returns summa & index
%,the index of first element of n consecutive ones.If n>v,then the function returns summa as 0 & index=-1.
%Example-[summa,index]=max_sum([1 2 3 4 5 4 3 2 1],3])
%summa=13
%index=4

function [summa,index]=max_sum(v,n)
total=0;
if n>v
    summa=0;
    index=-1;
    
else
    for ii=1:length(v)
        jj=ii+(n-1);
        if jj<=length(v)
        total=[total,sum(v(ii):v(jj))];     %Here I'm trying to create a row vector with sum of consecutive n integers
        end
    end
    [summa,index]=max(total);
end
end

[KSSV]

Your jj gets equals to 9. Where as your v is of size 1*8. Code tries to extract v(9) so the error.

[vidushi Chaudhary]

The code is working now,but it's giving incorrect value of summa(It is giving 12 for the above example..).What is wrong?

Answer 1

[Geoff Hayes]

vidushi - the problem is with this line

total=[total,sum(v(ii):v(jj))]; 

and in particular the inputs to the sum function. Here you are providing two integers (based on the input array) and using the : colon to produce an array of elements between these two. So if your two integers are 1 and 8, then

>> 1:8

ans =

     1     2     3     4     5     6     7     8

which is an array of eight integers which isn't what you want. Instead, you want to extract from v a subset or sub-array of consecurtive elements of length 3. So you need to do

total=[total,sum(v(ii:jj))];